Apparatus for reducing etching marks on solar cell surface

ABSTRACT

An apparatus for reducing etching marks on a solar cell surface includes an etching bath, an etchant-feeding pipe configured in the etching bath, and a bubble guiding device that covers the etchant-feeding pipe. The bubble guiding device guides bubbles discharged from the etchant-feeding pipe to move toward at least one end of the etchant-feeding pipe for reducing etching marks on the solar cell surface.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan application serial no. 100112653, filed on Apr. 12, 2011. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an apparatus for etching a solar cell. More particularly, the invention relates to an apparatus for reducing etching marks on a solar cell surface.

2. Description of Related Art

Solar cell is a clean energy source which can generate electricity directly from sunlight due to photoelectric effects. Currently, in various kinds of solar cell, the silicon solar cell has been developed and most extensively applied.

FIG. 1A to FIG. 1F are schematic cross-sectional views illustrating a process of manufacturing a conventional silicon solar cell. In most cases, surface texturing is performed on a silicon substrate 100, such that a front surface 102, a back surface 104, and sides 106 of the silicon substrate 100 all have a surface texture, as shown in FIG. 1A. A diffusion process is then performed on the silicon substrate 100, so as to form diffusion regions 108 (shown in FIG. 1B) respectively on the surfaces (including the front surface 102, the back surface 104, and the sides 106) of the silicon substrate 100. An isolation process is carried out to etch the diffusion regions 108 on the surfaces excluding the front surface 102 of the silicon substrate 100. Thereby, the back surface 104 a and the sides 106 a of the silicon substrate 100 do not have the diffusion region, so as to accomplish wafer edge isolation (shown in FIG. 1C). An anti-reflection layer 110 (shown in FIG. 1D) is formed on the diffusion region 108 of the front surface 102, and the surface of the anti-reflection layer 110 and the back surface 104 a of the silicon substrate 100 are respectively coated with conductive paste 112 and 114. A sintering process is performed, such that the conductive paste 112 and 114 is transformed into front and back electrodes 116 and 118. The front electrode 116 passes through the anti-reflection layer 110 and comes into contact with the diffusion region 108.

During the isolation process, an etching apparatus that can cyclically provide etchant is often applied. Given that bubbles pile up in an etchant-feeding pipe to a certain quantity during the etching process, the accumulative bubbles are likely to become large bubbles that may be unexpectedly discharged. Thereby, etching marks are indirectly generated on the silicon substrate 100, as indicated in FIG. 2A and FIG. 2B.

As shown in the top view of FIG. 2A, the etchant is in contact with the diffusion region 108 at the edge 200 of the silicon substrate 100 because the air bubbles up, such that the diffusion region 108 is etched, and that the appearance of the solar cell is ruined. What is worse, as indicated in the cross-sectional view of FIG. 2B, the diffusion region 108 at the edge 200 of the silicon substrate 100 is etched, and then the irradiation area of the solar cell is decreased. Accordingly, the photoelectric conversion efficiency is reduced.

SUMMARY OF THE INVENTION

In the invention, an apparatus for reducing etching marks on a solar cell surface is provided. By applying the apparatus, the etching marks caused by air bubbles are not formed on the solar cell surface.

In an embodiment of the invention, an apparatus for reducing etching marks on a solar cell surface is provided. The apparatus includes an etching bath, an etchant-feeding pipe configured in the etching bath, and a bubble guiding device covering the etchant-feeding pipe for guiding bubbles discharged from the etchant-feeding pipe to move toward at least one end of the etchant-feeding pipe.

According to an embodiment of the invention, the bubble guiding device includes a filter.

According to an embodiment of the invention, the bubble guiding device further includes a fixing member that is configured in the middle of the etchant-feeding pipe for fixing the filter.

According to an embodiment of the invention, the bubble guiding device further includes at least one supporting member that is configured at the end of the etchant-feeding pipe for supporting the filter.

According to an embodiment of the invention, a plurality of etchant outlets are configured between the ends of the etchant-feeding pipe.

According to an embodiment of the invention, the apparatus further includes an etchant-feeding bath that is connected to the etchant-feeding pipe, so as to continuously provide the etching bath with an etchant.

According to an embodiment of the invention, the apparatus further includes a motor for pumping the etchant from the etchant-feeding bath and moving the drawn etchant into the etching bath.

According to an embodiment of the invention, the apparatus further includes an etchant recycling pipe that is connected between the etching bath and the etchant-feeding bath, so as to cyclically provide the etchant.

According to an embodiment of the invention, the apparatus further includes a silicon substrate moving device that is configured above the etchant-feeding pipe in the etching bath.

According to an embodiment of the invention, the silicon substrate moving device includes a plurality of rollers for continuously moving a silicon substrate.

Based on the above, in the apparatus described in the embodiments of the invention, the bubble guiding device guides the bubbles discharged from the etchant-feeding pipe to move toward the ends of the etchant-feeding pipe, and thereby the etching marks caused by the bubbles are less likely to be formed on the solar cell surface.

Other features and advantages of the invention will be further understood from the further technological features disclosed by the embodiments of the invention wherein there are shown and described embodiments of this invention, simply by way of illustration of modes best suited to carry out the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1A to FIG. 1F are schematic cross-sectional views illustrating a process of manufacturing a conventional silicon solar cell.

FIG. 2A is a top view illustrating that the silicon substrate depicted in FIG. 1C has etching marks on an edge of the silicon substrate.

FIG. 2B is a cross-sectional view along a line B-B depicted in FIG. 2A.

FIG. 3 is a schematic view illustrating an apparatus for reducing etching marks on a solar cell surface according to an embodiment of the invention.

FIG. 4 is a schematic view illustrating an exemplary detailed structure of the bubble guiding device depicted in FIG. 3.

FIG. 5A and FIG. 5B are schematic views illustrating examples of the supporting member depicted in FIG. 4.

FIG. 6 is a schematic view illustrating that an etching process is performed by the apparatus for reducing the etching marks on the solar cell surface as shown in FIG. 3.

DESCRIPTION OF EMBODIMENTS

A description accompanied with the drawings is provided below to sufficiently explain embodiments of the invention. However, it is noted that the invention can still be implemented in many other different forms and should not be construed as limited to the embodiments described hereinafter. As a matter of fact, the embodiments are provided to render the disclosure of the invention more explicit and complete, so as to fully convey the scope of the invention to people having ordinary skill in the pertinent art. In the drawings, for the purpose of clarity, the dimensions and the relative dimensions of each component and each region may not be illustrated in accurate proportion.

FIG. 3 is a schematic view illustrating an apparatus for reducing etching marks on a solar cell surface according to an embodiment of the invention.

With reference to FIG. 3, an apparatus for reducing etching marks on a solar cell surface includes an etching bath 300, an etchant-feeding pipe 302 configured in the etching bath 300, and a bubble guiding device 304 covering the etchant-feeding pipe 302 for guiding bubbles 306 discharged from the etchant-feeding pipe 302 to move toward ends 308 of the etchant-feeding pipe 302. A plurality of etchant outlets 310 can be configured between the ends 308 of the etchant-feeding pipe 302. The apparatus further includes an etchant-feeding bath 312 that is connected to the etchant-feeding pipe 302, so as to continuously provide the etching bath 300 with an etchant 314. The etchant 314 can be pumped by a motor 316, and the pumped etchant 314 can be moved into the etching bath 300. Additionally, the apparatus can further include an etchant recycling pipe 318 that is connected between the etching bath 300 and the etchant-feeding bath 312, so as to cyclically provide the etchant 314.

FIG. 4 is a schematic view illustrating an exemplary detailed structure of the bubble guiding device 304 depicted in FIG. 3.

As indicated in FIG. 4, the bubble guiding device is a filter 400 made of a polypropylene (PP) material, for instance. The filter 400 allows the etchant to pass but blocks the bubbles. A fixing member 402 (e.g., an acid-resistant belt) can be further configured in the middle of the etchant-feeding pipe 302 for fixing the filter 400. Supporting members 404 can be configured at the ends 308 of the etchant-feeding pipe 302, so as to support the filter 400 and prevent the bubbles from piling up in the filter 400. The shape of the supporting members 404 is not limited in the invention as long as the supporting members 404 can ensure that the two ends 406 of the filter 400 remain open. For instance, the supporting member 404 can be a circular ring 500 that keeps the two ends 406 of the filter 400 completely open as shown in FIG. 5A, or a supporting cross 502 that holds the two ends 406 of the filter 400 as shown in FIG. 5B.

The effects of the invention are elaborated below. Specifically, an etching process is continuously performed on a silicon substrate by the apparatus depicted in FIG. 3.

FIG. 6 is a schematic view illustrating that an etching process is performed by the apparatus for reducing the etching marks on the solar cell surface as shown in FIG. 3.

With reference to FIG. 6, the apparatus not only includes the components depicted in FIG. 3 but also has a silicon substrate moving device 600 that is configured above the etchant-feeding pipe 302 in the etching bath 300. The silicon substrate moving device 600 has a plurality of rollers 602 for continuously moving a silicon substrate 604. When the silicon substrate 604 moves from one side of the etching bath 300 to the other, the level 606 of the etchant 314 is required to be in contact with the back surface 608 and the sides 610 of the silicon substrate 604, so as to perform an isolation process. In the meantime, given the bubbles in the etchant-feeding pipe 302 pile up to a certain quantity, and large bubbles 612 are discharged from the etchant outlets 310 of the etchant-feeding pipe 302, the bubble guiding device 304 guides the bubbles 612 to its two ends 406, such that the bubbles are eliminated or attenuated. As indicated in FIG. 6, the two ends 406 of the bubble guiding device 304 are located at regions which the silicon substrate 604 does not pass through. This further prevents the etching marks from being formed on the solar cell surface.

In view of the above, the etching apparatus applied in the etching process of the solar cell is improved in the invention. Thereby, the etching marks caused by the bubbles are far less likely to be formed on the solar cell surface. Further, by applying the etching apparatus described in the embodiments of the invention, it is no longer necessary to shut off the machine in order to discharge the bubbles.

Although the invention has been described with reference to the above embodiments, it will be apparent to one of the ordinary skill in the art that modifications to the described embodiments may be made without departing from the spirit of the invention. Accordingly, the scope of the invention will be defined by the attached claims rather than by the above detailed descriptions. 

1. An apparatus for reducing etching marks on a solar cell surface, the apparatus being adapted to a process of etching a solar cell, the apparatus at least comprising: an etching bath; an etchant-feeding pipe configured in the etching bath; and a bubble guiding device covering the etchant-feeding pipe, so as to guide bubbles discharged from the etchant-feeding pipe to move toward at least one end of the etchant-feeding pipe.
 2. The apparatus as claimed in claim 1, wherein the bubble guiding device comprises a filter.
 3. The apparatus as claimed in claim 2, wherein the bubble guiding device further comprises a fixing member configured in the middle of the etchant-feeding pipe for fixing the filter.
 4. The apparatus as claimed in claim 2, wherein the bubble guiding device further comprises at least one supporting member configured at the at least one end of the etchant-feeding pipe for supporting the filter.
 5. The apparatus as claimed in claim 1, wherein a plurality of etchant outlets are configured between the ends of the etchant-feeding pipe.
 6. The apparatus as claimed in claim 1, further comprising an etchant-feeding bath connected to the etchant-feeding pipe, so as to continuously provide the etching bath with an etchant.
 7. The apparatus as claimed in claim 6, further comprising a motor for pumping the etchant from the etchant-feeding bath and moving the pumped etchant into the etching bath.
 8. The apparatus as claimed in claim 6, further comprising an etchant recycling pipe connected between the etching bath and the etchant-feeding bath, so as to cyclically provide the etchant.
 9. The apparatus as claimed in claim 1, further comprising a silicon substrate moving device configured above the etchant-feeding pipe in the etching bath.
 10. The apparatus as claimed in claim 9, wherein the silicon substrate moving device comprises a plurality of rollers for continuously moving a silicon substrate. 